This invention relates generally to Global Positioning System (“GPS”) navigation systems, and more particularly to methods and apparatus for interconnecting additional data transmission systems with the GPS navigation system.
Electronic navigation devices employing Global Positioning System (“GPS”) receivers are known. The GPS includes a plurality of satellites that are in orbit about the earth. The orbit of each satellite is not necessarily synchronous with the orbits of other satellites and, in fact, is likely asynchronous. The GPS receiver device receives spread spectrum GPS satellite signals from the various satellites. The spread spectrum signals continuously transmitted from each satellite utilize a highly accurate frequency standard accomplished with an extremely accurate atomic clock. Each satellite, as part of its data signal transmission, transmits a data stream indicative of that particular satellite. The GPS receiver device acquires spread spectrum GPS satellite signals from at least three satellites to calculate its two-dimensional position by triangulation. Acquisition of an additional signal, resulting in signals from a total of four satellites, permits the GPS receiver device to calculate its three-dimensional position. In this manner, an electronic navigation device employing a GPS receiver has the ability to accurately compute the position of the device in real time, even as the device moves.
GPS receivers may also have the ability to receive and process data from the Wide Area Augmentation System (“WAAS”). The WAAS uses a system of satellite and ground stations that provide GPS signal corrections to provide a consumer with better position accuracy.
Many handheld electronic navigation devices are presently on the market. Some consumers readily carry such handheld electronic navigation devices with them when they are traveling in their vehicles in order to enjoy the benefit of navigational aids while driving. By way of example only, the navigation device may be designed to plug into the 12 Volt outlet in an automobile. The handheld electronic navigation devices may also include a battery and be used when on foot, such as when hiking or shopping.
Consumers also enjoy technologies such as satellite radio data. Satellite radio data is provided by companies such as XM and Sirius, and offer the consumer the ability to receive radio stations, traffic, weather, stock reports, and other information via a combination of satellites and repeaters installed on the ground. The consumer can choose from many different stations and tailor the content to their tastes.
Real-time traffic and weather information is also broadcast over the FM radio data system by, for example, the Traffic Message Channel (“TMC”) in Europe and Clear Channel Communications, Inc. (CC) in the United States. Thus, the GPS, XM, CC, and TMC systems each transmit data using unique data transmission systems, or schemes. It should be understood that other data transmission systems exist and/or may be in development which the consumer may wish to access for entertainment, assistance, and/or information. Each system has the potential for transmitting information useful to a consumer, but the full benefit of each system cannot be realized by using the systems separately.
Therefore, a need exists for a navigation system which integrates GPS navigation information with data received from additional data transmission systems. Furthermore, there exists a need for an apparatus to easily accomplish the integration of external data transmission systems with little or no input from the consumer. Certain embodiments of the present invention are intended to meet these needs and other objectives that will become apparent from the description and drawings set forth below.